Cancer immunotherapy refers to methods of activating the immune system to induce tumor regression and disease stabilization (Mellman I et al., Nature. 480, 7378: 480-9 (2011)). Antibody therapy directed against certain negative immunologic regulators (immune checkpoints) has been shown to be successful as an anti-tumor treatment in several cancer types (Postow et al., J Clin Oncol 33: 9, (2015)).
The transforming growth factor beta (TGFβ) protein family consists of three distinct isoforms found in mammals (TGFβ1, TGFβ2, and TGFβ3). The TGFβ proteins activate and regulate multiple gene responses that influence disease states, including cell proliferative, inflammatory, and cardiovascular conditions. TGFβ is a multifunctional cytokine originally named for its ability to transform normal fibroblasts to cells capable of anchorage-independent growth. The TGFβ molecules are produced primarily by hematopoietic and tumor cells and can regulate, i.e., stimulate or inhibit, the growth and differentiation of cells from a variety of both normal and neoplastic tissue origins (Sporn et al., Science, 233: 532 (1986)), and stimulate the formation and expansion of various stromal cells.
The TGFβs are known to be involved in many proliferative and non-proliferative cellular processes such as cell proliferation and differentiation, embryonic development, extracellular matrix formation, bone development, wound healing, hematopoiesis, and immune and inflammatory responses. See e.g., Pircher et al, Biochem. Biophys. Res. Commun., 136: 30-37 (1986); Wakefield et al., Growth Factors, 1: 203-218 (1989); Roberts and Sporn, pp 419-472 in Handbook of Experimental Pharmacology eds M. B. Sporn & A. B. Roberts (Springer, Heidelberg, 1990); Massague et al., Annual Rev. Cell Biol., 6: 597-646 (1990); Singer and Clark, New Eng. J. Med., 341: 738-745 (1999). Also, TGFβ is used in the treatment and prevention of diseases of the intestinal mucosa (WO 2001/24813). TGFβ is also known to have strong immunosuppressive effects on various immunologic cell types, including cytotoxic T lymphocyte (CTL) inhibition (Ranges et al., J. Exp. Med., 166: 991, 1987), Espevik et al., J. Immunol., 140: 2312, 1988), depressed B cell lymphopoiesis and kappa light-chain expression (Lee et al., J. Exp. Med., 166: 1290, 1987), negative regulation of hematopoiesis (Sing et al., Blood, 72: 1504, 1988), down-regulation of HLA-DR expression on tumor cells (Czarniecki et al., J. Immunol., 140: 4217, 1988), and inhibition of the proliferation of antigen-activated B lymphocytes in response to B-cell growth factor (Petit-Koskas et al., Eur. J. Immunol., 18: 111, 1988). See also U.S. Pat. No. 7,527,791.
TGFβ isoform expression in cancer is complex and variable with different combinations of TGFβ isoforms having different roles in particular cancers. TGFβ molecules can act both as tumor suppressors and tumor promoters. For example, deletion or downregulation of TGFβ signaling in animals can result in increased breast cancer, intestinal cancer, pancreatic cancer, colon cancer and squamous cell carcinoma, indicating the presence of TGFβ is important to prevent or slow tumor progression (Yang et al., Trends Immunol 31:220-27, 2010). However, overexpression of TGFβ is known to be pro-oncogenic and increased expression is detected in many tumor types (Yang et al., supra).
Antibodies to TGFβ have been described in U.S. Pat. Nos. 7,527,791; 7,927,593; 7,494,651; 7,369,111; 7,151,169; 6,492,497; 6,419,928; 6,090,383; 5,783,185; 5,772,998; 5,571,714; and U.S. Pat. Nos. 7,723,486 and 8,569,462.
Programmed cell death protein 1 (PD-1), also known as cluster of differentiation 279 (CD279), is a cell surface co-inhibitory receptor expressed on activated T cells, B cells and macrophages, and is a component of immune checkpoint blockade (Shinohara et al., Genomics., 23(3):704, (1994); Francisco et al., Immunol Rev., 236: 219, (2010)). PD-1 limits the activity of T cells upon interaction with its two ligands PD-L1 (also known as B7-H1; CD274) and PD-L2 (B7-DC; CD273) (Postow et al., J Clin Oncol., 33: 9, (2015)). Interaction of PD-1 with PD-L1 and PD-L2, reduces T-cell proliferation, cytokine production, and cytotoxic activity (Freeman G J et al., J Exp Med., 192:1027-34, (2000); Brown J A et al., J Immunol., 170:1257-66, (2003)).
Recently, two monoclonal antibodies have been approved by the U.S. Food and Drug Administration (FDA) for the inhibition of PD-1 immunotherapy. Pembrolizumab (KEYTRUDA®, Merck Sharp & Dohme Corp.) is approved for use in metastatic melanoma, and nivolumab (Opdivo®, Bristol-Myers Squibb) is approved for use in metastatic melanoma and metastatic squamous non-small cell lung cancer (NSCLC). Both of these antibodies bind to the PD-1 receptor and block its interaction with its ligands, PD-L1 and PD-L2.
Inhibitors of PD-L1 have also been shown to be effective at inhibiting solid tumors in bladder cancer, head and neck cancer, and gastrointestinal cancers (Herbst R S et al., J Clin Oncol., 31: 3000 (2013); Heery C R et al., J Clin Oncol., 32: 5s, 3064 (2014); Powles T et al., J Clin Oncol, 32: 5s, 5011(2014); Segal N H et al., J Clin Oncol., 32: 5s, 3002 (2014)).
Antibodies to PD-1 have been described in U.S. Pat. Nos. 8,735,553; 8,617,546; 8,008,449; 8,741,295; 8,552,154; 8,354,509; 8,779,105; 7,563,869; 8,287,856; 8,927,697; 8,088,905; 7,595,048; 8,168,179; 6,808,710; 7,943,743; 8,246,955; and 8,217,149.
In the setting of cancer, multiple mechanisms of immune suppression may prevent immunotherapy from being effective. In some cases tumors are refractory to mono-immunotherapy and only a minor fraction of cancers fully respond. Therefore the use of combinations of immunotherapeutic agents will likely be required for optimal patient responses (Hodi F S et al., Adv Immunol., 90:341-68, 2006; Postow et al., J Clin Oncol., 33: 9, 2015).
Recently TGFβ inhibition combined with inhibition of immune checkpoint protein CTLA-4 has been demonstrated to be effective at suppressing melanoma tumor growth and metastasis (Hanks et al., J Clin Oncol 32: 5s, 2014). Combinational immunotherapy approaches using inhibitors of PD-1/PD-L1 and CTLA-4 are currently being evaluated (Sznol M et al., J Clin Oncol., 32: 5s, 2014; Wolchok J D et al., N Engl J Med., 369: 122-133, 2013; Callahan et al., J Clin Oncol., 32:5s, 2014 and reviewed in Postow et al., J Clin Oncol., 33: 9, (2015)). Studies have described synergistic upregulation of IFNγ in effector T cells from tumor-draining lymph nodes following simultaneous blockade of PD-L1 and TGFβ using a combination of monoclonal antibodies implicating PD-L1 and TGFβ in suppressing cellular responses to active immunization in the tumor-bearing host (Wei et al., Cancer Res, 68: 13, 2008).